Hoist attachments



Oct.A 12, 1965 E. c. GARDNER ETAL 3,211,490

HoIsT ATTACHMENTS Filed April 1, 1965 5 Sheets-Sheet 1 I I J3 f//We C'. Gara/nef* fafa/7e A. Manif/Kaffe# fA/l/fA/O/PJ Oct. 12, 1965 E. c. GARDNER ETAL 3,211,490

HOIST ATTAGHMENTS Filed April l, 1963 5 Sheets-Sheet 2 ATT/CP/VEVJ Oct. 12, 1965 E. c. GARDNER l-:TAL 3,211,490

HOIST ATTACHMENTS 5 Sheets-Sheet 5 Filed April 1, 1963 f/m er C. Gard/7er fay'ene A. H0

INVENFORJ` @M1 M JW United States Patent O 3,211,490 HOIST ATTACHNIENTS Elmer C. Gardner and Eugene A. Horstketter, Houston, Tex., assignors to Gardner Engineering Corporation, Houston, Tex., a corporation of Texas Filed Apr. 1, 1963, Ser. No. 269,610 Claims. (Cl. 294-88) The present invention relates to hoist attachments, and more particularly to hoist attachments for hooking and carrying heavy loads.

During the construction of massive vstructures such as dams and skyscrapers, large amounts of construction material must be moved from one place to another. One of the more common materials used in buildings is coucrete poured at the construction site. It is well known to mix the concrete, for example, at ground level where such mixing can be conveniently accomplished and then hoist the mixed concrete to a higher elevation or another location for pouring. The usual procedure is to till a bucket or other container with mixed concrete and then move the bucket to the pouring site. The common practice is to use a crane having a hook which is attached to the bail of a material bucket. Several buckets are frequently used to permit filling one bucket while another is transported to the pouring site. The use of several buckets requires releasing an empty bucket at the mixing station and hooking a lled bucket for transporting to the pouring site where the filled bucket is released and an empty bucket is hooked for return to the mixing station.

Using this procedure, it is necessary to provide a hook man to manually guide the crane hook into engagement with the bail of a bucket to be hoisted. When the hook is properly positioned, the hook man signals the crane operator that the load is secured, and the bucket is then hoisted and moved to the desired location.

When very large loads are carried, it is frequently difficult for the crane operator to precisely control the position of the load during hoisting and swinging of the crane. This lack of control is aggravated by obstructions, such as the existing superstructure of the project under construction. Due to these conditions, the material bucket or other carried load sometimes hits an obstruction with the result that the bucket is accidentally unhooked or released. Since the hoisted load is frequently several tons, extensive damage and serious injury can be caused by accidentally dropping the bucket. Similar accidents can occur while positioning the load at the pouring site. For example, the load could bump the edge of the pouring platform and accidentally unhook.

Where the hook is power operated to hooking and releasing position, the operation of the hook is usually remotely controlled by the crane operator. Here again, serious accidents have occurred when inadvertent operation of the hook control caused the load to be released in mid-air.

The present invention obviates the problems encountered with hoist attachments used in the past. With the hoist attachment of the present invention, the hooking and releasing operations are wholly controlled from a remote location by an operator who could be the crane operator. The formerly used hook man is no longer necessary since the hoisting attachment is provided with guide members which accurately center the attachment relative to a material bucket so that the bucket can be positively hooked. During the transport of the bucket, there is no danger of accidental release of the hook since the present invention includes two safety locks which positively prevent accidental release of a load by inadvertent striking of an obstruction, by accidental opera- 3,211,490 Patented Oct. 12, 1965 ICC tion of the hook control, or by a power failure which would render the hook control inoperable. In fact, while the load is supported by the hooking attachment, the load cannot be released even if it is desired to do so. Among the improved features of the present invention is a material bucket of unique construction which is especially adapted to be used with the hooking device of the present invention.

Accordingly, an object of the present invention is to provide a hoist attachment for hooking and carrying heavy loads which can be remotely controlled by the operator of the hoisting device.

Another object of the present invention is to provide a hoist attachment which includes a safety hook mechanism that will not release a lifted load as long as the weight of the load is carried by the attachment.

Another object of the present invention is to provide a hoist attachment for hooking and lifting heavy loads which includes guide members associated therewith to facilitate centering the attachment relative to a loadto be hooked.

A further object of the present invention is to provide a hoist attachment which, when centered above the bail, will readily attach itself regardless of the rotational relationship between the hook and the bail.

Another object of the present invention is to provide a safety hoist attachment for lifting heavy loads that is pneumatically controlled from a remote location and will not release a lifted load if the hook-operating apparatus is inadvertently actuated.

A further object of the present invention is to provide an improved material container having a unique bail adapted to be hooked by the improved safety hoist attachment of the present invention.

A further object of the present invention is to provide a safety hoist attachment which is rugged in structure, is easy to position relative to a load and can be securely locked to the load for hoisting.

A still further `object of the present invention is to provide a safety hoist attachment in which the configurations of the hooks and container bail are so interrelated as to positively prevent releasing of a load while the load is suspended. y

In order that the manner in which these and other objects are attained in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this speciication, and wherein:

FIG. 1 is a side elevational view in section of a portion of the hoist attachment of the present invention showing the relationship of the various parts of the attachment when a load is hooked;

FIG. 2 is a side elevational view in section of a. portion of the hoist attachment of the present invention showing the relationship of the various parts of the attachment when a load is released;

FIG. 3 is a side elevational view in section of a portion of the hoist attachment of the present invention showing the relationship of the various parts of the attachment when in a position intermediate that of FIGS. 1 and 2;

FIG. 4 is a view in exploded perspective showing the various parts of the safety hoist attachment of the present invention;

FIG. 5 is a horizontal sectional view taken substantially on line 5 5 of FIG. l, showing the -hoist attachment of the present invention and a material container especially adapted to be hooked by the attachment;

FIG. 6 is a sectional View taken substantially on line 6 6 of FIG. 2, showing a front view of a single hook; and

FIG. 7 is a partial sectional view taken substantially on line l7--7 of IFIG. 2 showing a portion of the lower end of the uid cylinder of the present invention.

Referring now to the drawings in detail, and particularly to FIG. 1, there is shown a -hoist attach-ment cornprising a frame 1, a hook 2 pivotally carried by the frame, a motor 3 movable relative to the frame, a hook operating mechanism 4 actuated by the motor, and a hook locking mechanism 5 also actuated by the motor.

Although the hooking device of the present invention hasl other uses, it is particularly adapted for use with a material container 6 having a generally horizontally disposed circular bail 7 spacedabove the top end of the material container and rigidly attached to the container by connecting members 8.

'Frame 1 comprises a hollow, elongated, cylindrical support member 9 securely fastened to a hook support and guide assembly 10. `Cylindrical support member 9` has an elongated tubular body 11 closed at its upper end by a circular plate 12 and is open at its lower end 13. Extending upwardly froml the bottom end 13 of tubular body 11 are .three identical guide slots 14 cut completely through the side wall of tubular body 11. The slots 14 are equally spaced circumferentially and extend longitudinally about one-half the length of tubular `body 11. Securely attached by welding to tubular body 9adjacent sidel edges 14 of the slots are a plurality of flat, elongated reinforcing members 15. Reinforcing members 15 are arranged in parallel pairs yand extend outwardly from tubular body 11. Inner surfaces 15 of the reinforcing members are substantially smooth and are aligned with the side edges 14 of slots 14 tol guide the moving parts of hook operating mechanism 4 and hook locking mechanism 5. Secured to circular plate 12 of cylindrical supe port member 9 is a connecting member 16 having apertures 17 and 18. Threaded through aperture 17 is a main lload supporting wire rope 19 which extends to a hoisting device, for example a crane (not shown), and connected in aperture 18 is a sway-preventing wire line 20 which in the preferred embodiment, ythe arms are spaced at angles of 120 relative to each other.

. vEach arm 21 comprises a pair of structural steel side plates 23, 24 which are connected in spaced parallel relation by end plate 25, bottom plate 26 and vertical plate 27. The plates 25, 26 and 27, which are also of structural steel, are secured to side plates 23 as by welding to form a very rigid structure. The width of arms 21 from the outer surfaces of plates 23 and 24 is slightly less than the width of slots 14 so that cylindrical support 9 can be aligned with and slipped over the arms. When so assembled, the hook support and guide assembly 10 is secured to cylindrical support 9 by threaded fasteners 2'7 passing through fastener receiving openings 28 and 28', 1

respectively, in reinforcing members 15 and arms 21.

Side plates 23, 24of arms 21 -have a -generally rectangular tip portion 29 adjacent their outer ends dened between top edges 29 and bottom edges-30. Trapezoidalshaped, downwardly depending portions 31 are defined by straight edges 32 which slope inwardly toward vertical plates 27 and terminate at horizontal bottom edges 33.

Fluid motor 3 is a single acting pneumatic cylinder dis-l posed vertically within tubular body 11 of cylindrical support member 9. Motor 3 comprises a tubular body 34 with a cup-shaped end cap 35 threaded on one end and a cup-shaped end cap 36 threaded .on the other end. A piston 37 is slvidably disposed inside tubular body 34 and is normally biased down toward end cap 36 by the action of compression spring 38 acting on top face 39 of the 'piston and the undersurface of end cap 3,5. A piston rod 40 is attached to the lower face 41 of the piston and extends downwardly through a packed bore 42 of end cap 36. Piston 37 is provided with suitable packing 43 to prevent escape of operating tluid from the annular space between the piston and end cap 36 to the region above the piston.

A pipe 44 is threaded into a bore in end cap 36 to supply fluid to the cylinder. One end of a flexible hose 45 is connected to pipe 44. Hose 45 extends downwardly within cylindrical support 9 and then extends through an opening (not shown) in the side wall of tubular body 9. The other end of hose 44 is connected to valve 46 which is at a location remote 4from the hoist attachment, for example in the cab of a crane (not shown) used for lifting the attach-ment. A suitable source of fluid, for example compressor 47, supplies air to valve 46. Valve 46 is preferably a two-way valve operable to supply fluid from compressor 47 to motor 3 when the valve is open, and exhaust fluid Ifrom motor 3 when the valve is closed.

There are three hooks 2, one pivotally carried by each arm 21. Each hook 2 `has a Ibody 48 with a curved portion 49 at one side of the body, terminating in an upwardly extending vhook point 50. The curved portion 49 has an upwardly facing arcuate surface 51 for supporting bail 7 of material container 6. A portion of body 48 extends over surface 51 and has an eye 52 which receives journal pin 53 for pivotally mounting the hook on arm 21. A bore 54 spaced above and slightly offset from eye 52 is provided with pin 55 to connect hook 2 to actuating mechanism 4. Body 48 is laterally enlarged at the side of the hook opposite hook point 50 and has an arcuate lower edge 56 terminating at a step 57 at the back of the hook. The edge 56 has the curvature of an arc of a circle with an axis of pin 53 as a center. An upper edge 58 of the -back of hook 2 is straight and slopes away from step 56.

Hook actuating mechanism 4 comprises a connecting member 59 and links 60. Connecting member 59 has an upright tubularY side wall 61 terminating at an inwardly extending top flange 62. Connecting member 59 is secured to motor 3 by bolts 62 passing through bores 63, the bolts being threaded into end cap 36.

Projecting radially from side wall 61 of connecting member 59 are three ears 64 reinforced by gussets 65.. Each ear 64 is circumferentially aligned to pass through `guide slot 14 to lie between reinforcing members 15. A at ring 65 is attached to the bottom edge of tubular side wall 61.

Each link 60 comprises a pair of at, spaced apart side members 66 and 67 having their upper edges connected by plates 68 and 69. The lowerend of link 60 is pivotally connected to hook 2 by pin 55 passing through aligned pin-receiving bores in side members 66 and 67. The lupper end of link 60 is pivotally connected to connecting member 59 by a pin 70 passing through ear 64 and aligned bores in members 66 and 67. e

As best seen in FIG. 6, the width of link 60 is slightly less than the distance between the inner surfaces of side plates 23 and 24 of arm 21 so that the lower end of link 6 0 has sufficient clearance to slide between the side plates. The side members 66 and 67 are relatively thinl and are spaced apart a distance slightly greater than the width of hook 2 to provide clearance between llat sides 58 of the hook and the inner surfaces of side members 66 and 67. Side members 66 and 67 extend between the sides of hook 2 and the inner surfaces tof side plates 23 and 24 and function to center the hook between the side plates at pin 55. Bodyl 48 of the hook is centered by guides 70' projecting inwardly from the inner surfaces of plates 23 and 24. Guides 70 extendA upwardly from edge 32 to perform their guiding function throughout the pivotal movement of the. hook from the load liftingl position of FIG. l to the load' releasing position of FIG. 2. Since the hook is of uniform width and has flat sides 58', it will be apparent that lthe hook is maintained in a centered position relative to side plates 23 and 24 by guides 70 and side members 66 and 67.

Hook locking mechanism 5 includes a lock operating member 71 and links 72. Lock operating member 71 comprises a central shaft 72' which is axially aligned with and threaded to piston rod 40. Secured to shaft 72 are three radially projecting legs 73 which are circumferentially 'spaced to extend through slots 14 in support member 9. A flat ring 74 concentric with tubular body 11 is secured as by welding to a portion of the ltop edges of legs 73. Shaft 72 extends downwardly into and is guided by a vertical bore 75 in cylindrical member 22.

Links 72 are shorter than links 60 and comprise spaced apart parallel side members 76 and 77 connected by plate 78. The upper end of each link 72 has aligned bores in side members 76 and 77 to pivotally connect the link to pins 79 in legs 73. The lower end of each link 72 has aligned bores 80 to receive stop pin 81 which extends beyond the outer surfaces of side members 76 and 77. The ends of stop pin 81 extend into a pair of aligned elongated slots 82 in side plates 23 of arm 21. Slots 82 slope slightly upwardly toward the axis of the attachment and function to limit the movement of the lower end of link 72.

As best seen in FIG. 1, the flat stop surface of step 57 of hook 2 is substantially coplanar with the lower edges of slot 82 when the hook is in a load lifting position. The stop surface of step 57 lies at an angle of less than 90 to arcuate edge 56 which has its center of curvature at the axis of journal pin 53. Since the only possible motion of hook 2 is to pivot about pin 53, any force exerted on stop pin 81 by step 57 will tend to move the pin slightly toward the hook into more secure locking engagement. Hence, any forces tending to pivot the hook are resisted solely by the reaction of the upper edges of slots 82 against the ends of pin 81. Stop pins 81 are thus effective to positively prevent any movement of hooks 2 when the pins are positioned above step surfaces 57.

By virtue of the unique construction of the hoist attachment of this invention, the attachment is easy to assemble, and disassemble should servicing be necessary. The preferred procedure for assembly is to first attach link 60 to a hook 2 by inserting a pin 55 through the lower end `of the link and bore 54 of the hook. A hook 2 is then pivoted to an arm 21 by aligning eye 52 with bores 83 (FIG. 4), adjacent the outer ends of the arm, and inserting journal pin 53. Pin 53 is fastened by any well known means, for example, with `Cotter pins (not shown). Since pin 55 which connects link 60 to the hook is slightly shorter than the distance between the inside surfaces of plates 23 and 24, the pin cannot slide laterally out of the hook and hence, need not be fastened. This procedure is followed for each of the three hooks.

Shaft 72 of lock operating member 71 is inserted in bore 75 so that the lower edges of legs 73 abut a top surface 84 of an outwardly extending flange 85 of cylindrical member 22. One end of a link 72 is pinned to a leg 73 and the link is then aligned with the space between side plates 23 and 24 and is lowered to permit insertion of stop pin 81 from one side of arm 21. The other two links 72 are then pinned to legs 73 and their respective stop pins 81 are inserted. The stop pins 81 can be fastened with cotter pins (not shown).

Connecting member 59 is then bolted to motor 3 and supply pipe 44 is threaded into end cap 36. Piston rod 40 is threaded to shaft 72 and the assembly is rotated so that ears 64 are radially aligned with arms 21. A force is then applied to the top of motor 3 to overcome the bias of spring 38 thereby moving connecting member 59 downwardly so that the upper ends of links 60 can be pinned to ears 64.

Cylindrical support 9 is then axially aligned with motor 3 and is slipped over the assembly so that slots 14 are radially aligned with arms 21. Threaded fasteners 27 are then inserted to secure the arms to support 9. Connecting 6 plate 16 can be secured to the cylindrical support, preferably by welding, either before or after the support is attached to arms 21. When hose 45 is then connected to valve 46 and wire ropes 19 and 20 are attached to connecting plate 16, the hoist attachment is ready for operation.

It is to be particularly noted that reinforcing members 15 serve the dual purpose of connecting support 9 to arms 21 and providing guide surfaces at each side of slots 14 to maintain ears 64 and legs 73 radially aligned with arms 21. Because the space between members 15 is only slightly greater than the length of pins 70 and 79, these pins need not be fastened but can be free floating, lateral movement of the pins being prevented by the inner surfaces of members 15. Washers 86 (FIG. 5) are placed on each side of legs 73 to center the legs relative to links 72 at pins 79. Also of importance is that motor 3, connecting member 59 and locking member 71 are not secured to cylindrical support 9 and therefore are free to slide along the axis of cylindrical support 9.

Operation As shown in FIG. 1, spring 38 holds the upper end of motor 3 against a resilient neoprene disc 87 disposed in cylindrical support 9 adjacent its top end. Resilient disc 87 prevents damage to end cap 35 by cushioning the motion of motor 3 at the end of its travel to the load lifting position of FIG. 1. In this loaded position, spring 38 also holds locking member 71 against top surface 84 of flange so that stop pins 81 lie over step 57 of each hook 2. The surface of step 57 provides a stop surface which engages stop pin 81 to positively prevent any pivotal movement of the hook inwardly toward the load release position of FIG. 2. Since any pivotal movement of the hook is resisted only by the reaction of top edges of slots 82 on stop pins 81, as previously explained, it follows that no forces are transmitted along links 72 which would tend to move the pins radially inwardly and, hence, the hooks are positively locked.

As will be noted in FIG. l, circular plate 12 and resilient neoprene disc 87 disposed in cylinder support 9 adjacent its top end are so located as to limit the upward travel of motor 3 to a position where hooks 2 are in lifting position and cannot travel outwardly past said position and therefore pin 55 cannot cross center of knuckle over pin 53.

To release a carried load, the attachment must first be lowered to support the load on a horizontal surface so that the hook points 50 are below the plane of ring bail 7. When so positioned, operation of valve 46 causes fluid from compressor 47 to enter the space between the lower face 41 of piston 37 and bottom end cap 36. The fluid tends to move body 34 down and piston 37 up. However, body 34 cannot move until the hooks are free to pivot, and the hooks cannot pivot until stop pins 81 are moved radially inwardly of step 57 of the hook. Hence, the fluid will first act to lift piston 37 and lock member 71 until stop pins 81 engage the radial inner surfaces of slots 82. In this position, as shown in FIG. 3, the stop pins 81 no longer prevent the hooks from pivoting but do prevent further upward movement of the piston. The action of the fluid is then effective to move the body 34 of motor 3 downwardly. Downward movement of body 34 establishes forces along links 60 which pivot hooks 2. to the release position of FIG. 2, the travel of the body 34 being limited by engagement of flat ring 65' with stop ring 74. As hook 2 pivots, the curved edge 56 of the bottom of the hook is closely adjacent stop pin 81 and thus prevents the stop pin from moving back to its initial position when flat ring 65 abuts stop ring 74. Hence, it can be seen that actuation of motor 3 sequentially unlocks the hooks and pivots the hooks to a released position. As the hooks are pivoted, the spring 38 is compressed and is effective to return the various parts to the load lifting position of FIG. 1, when the valve 46 is operated to exhaust fluid from motor 3.

When a load is engaged, the attachment is suspended above bail 7 of material container 6 with the hooks held in the released position by fluid from compressor 47. In the released position, the hooks are wholly within edges 30 and 32 of arms 21. When the attachment is approximately centered relative to the container, rope 19 is slackened to allow the attachment to move down until the attachment is supported on edges 30 by ring bail 7. If the attachment is slightly olf center relative to bail 7 as the attachment is lowered, this is of no import since converging edges 32 guide the attachment to the center of the bail. When valve 46 is operated to exhaust fluid from motor 3, body 34 moves up, due to the action of spring 38, until cap 35 strikes resilient disc 87. In this position, the hooks are fully extended and steps 57 have moved below stop pins 81, allowing the pins to move radially outwardly to lock the hooks in position. Again, the operation is sequential, the hooks being fully extended before the stop pins can move into locking engagement with the hooks. When the attachment is lifted, the hooks will securely engage the load as shown in FIG, 1.

Material bucket 6, as shown in FIGS. 1 and 5, has a tapered cylindrical side wall 87 with an open top S8 terminating at top edge v89. Bail connecting members 8 are secured to bail 7 and to top edge 89 to maintain the bail spaced above the top edge of the container. There are four connecting members 8 each disposed 90 from the other around the top of the container. The connect* ing members are circumferentially narrow and have a sharp inner edge 90 with sloping sides 91 to facilitate angularly positioning the attachment so that the hooks will not normally strike one of the connecting members when the hooks are extended. In the rare instances when one of the hooks is aligned with and strikes an edge 90 of connecting member 8, the operator need only release the hooks and then reorient the attachment so that the hooks will pivot to their fully extended load carrying position. Since bail 7 is slightly smaller in diameter than the open top of the container, there is a large substantially unobstructed circular opening which facilitates filling the container with liquidr concrete or other material. The bottom end of the container is closed by a at end wall 92.

In addition to the locking of the hooks effected by the action of pins 81, there is a second safety feature which prevents the hooks from pivoting should the motor 3 be inadvertently actuated while a load is supported by the attachment. This second safety feature is the result of extending hook points 50 above the center line of bail 7 so that surface 51 has a curvature which is greater than a semicircle. Then the inner surface of the hook point will l engage with the side of the bail and thus prevent pivoting the hooks until the load is otherwise supported to allow the hook points to drop below the bail.

Although the apparatus described is particularly useful for lifting and carrying material buckets of the type described, it may be used advantageously with other loads.

Though one advantageous embodiment has been chosen for illustrative purposes, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. A power operated safety hoist attachment comprising in combination a frame comprising a tubular member having a vertical axis and including means for attaching said member to a hoisting device, and

a plurality of circumferentially spaced arms extending radially from said tubular member and secured thereto,

a motor carried within said tubular lmember and movable with respect thereto along the axis of said tubular member,

a plurality of load supporting members, each said member being pivotally carried by one of said spaced arms and each being operatively arranged for actuation to a first position in which a load is hooked, and a second position in which the load is released,

means operatively interconnecting said motor with each of said load supporting members to simultaneously pivot said load supporting members from one of said positions to the other when said motor is operated, and

locking means operatively connected to said motor to prevent pivotal movement `of said load supporting members when said members are actuated to said rst position.

Z. A power operated safety hoist attachment in accordance with claim 1 in which said load supporting members are hooks,

and said locking means are stop members movable into engagement with a portion of each of said hooks.

3. A power operated safety hoist attachment in accordance with claim 1 which further includes guide means carried by said frame for centering said safety hoist attachment relative to a load to be hooked.

4. A power operated safety hoist attachment as defined by claim 1 in combination with a material container compnsing:

an uncovered bucket including a generally cylindrical side wall having an upper end terminating in a top edge, and

a flat substantially horizontal bottom end wall;

a generally horizontal bail in the form of a ring spaced veitically above said upper end of said side wall; an

circumferentially narrow connecting means rigidly securing said bail to said upper end,

whereby at least a portion of load supporting member can be disposed between said bucket and said bail to lift the material container.

5. The combination of claim 4 wherein:

said load supporting members are hooks, and

said locking means are stop members movable into engagement with a portion of each of said hooks.

6. The combination of claim 4 which further includes:

guide means carried by 'said frame for centering said safety hoist attachment relative to a load t0 be hooked.

7. A safety hoist attachment for lifting heavy loads comprising a frame including a hollow cylindrical support having a longitudinal axis, and

a plurality of elongate arms projecting radially outwardly from said support and secured thereto;

a plurality of hooks, one pivotally carried by each of said arms, l

each of said hooks including a curved lower portion terminating at one side in an upwardly extending hook point to define an rcuate upwardly facing load supporting surace,

a laterally enlarged body extending upwardly from the other side of said curved lower portion with at least a portion of said body extending inwardly above said load supporting surface,

an eye in said inwardly extending portion 0f said body to pivotally mount said hook, and

a stop surface on a peripheral edge of said hook at a point remote from said hook point;

a rst member disposed within said cylindrical suppgrt for movement along the longitudinal axis there- 0 s a plurality of links operatively interconnecting each of said piovtally carried hooks to said rst member to simultaneously pivot said hooks when said rst member is actuated;

a Second member disposed Within said cylindrical support for movement along the longitudinal axis thereof;

locking means extending from said second member to each of said arms to engage with said stop surfaces of said hooks when the hooks are pivoted to a load carrying position,

said locking means being effective to prevent pivotal movement of said hooks when engaged with said stop surfaces; and

means to operate said rst and second members to sequentially pivot said hooks and actuate said locking means.

8. A safety hoist attachment in accordance with claim 7 in which said locking means are a plurality of links having pins at the ends thereof adjacent said hooks to engage with the stop surfaces of said hooks, and

said hooks have an arcuately curved surface adjacent said stop surface to prevent movement of said locking means until said hooks are pivoted to a load carrying position.

9. A safety hoist attachment in accordance with claim 7 in which said means to operate said rst and second members is a uid operated motor.

10. A safety hoist attachment as defined by claim 7 in combination with a material bucket comprising:

a container portion including a generally cylindrical side wall having an upper end terminating in a top edge, and a flat substantially horizontal bottom end wall; a generally horiozntal bail in the form of a ring spaced from said side wall; and circumferentially narrow connecting means rigidly securing said bail to said container portion, whereby the plurality of hooks of said hoist attachment can be disposed between said container portion and said bail to lift the material bucket.

References Cited bythe Examiner UNITED STATES PATENTS 1,237,093 8/17 Priddy 220-94 X 1,270,995 7/ 18 Weickel 294-67 1,500,903 7/ 24 Shipley 294--81 2,349,689 5/ 44 Aldrich 294-97 2,613,847 10/52 Lacher 220-94 2,789,858 4/57 Kughler 294-81 3,025,996 3/ 62 Habicht 220-94 3,057,652 10/ 62 Getner et al 294-83 3,078,115 2/ 63 Harlander et al 294-67 FOREIGN PATENTS 1,178,214 12/58 France.

11,183 1893 Germany.

M. HENSON WOOD, IR., Primary Examiner.

ANDRES H. NIELSEN, ROBERT B. REEVES,

Examiners. 

1. A POWER OPERATED SAFETY HOIST ATTACHMENT COMPRISING IN COMBINATION A FRAME COMPRISING A TUBULAR MEMBER HAVING A VERTICAL AXIS AND INCLUDING MEANS FOR ATTACHING SAID MEMBER TO A HOISTING DEVICE, AND A PLURALITY OF CIRCUMFERENTIALLY SPACED ARMS EXTENDING RADIALLY RADIALLY FROM SAID TUBULAR MEMBER AND SECURED THERETO, A MOTOR CARRIED WITHIN SAID TUBULAR MEMBER AND MOVABLE WITH RESPECT THERETO ALONG THE AXIS OF SAID TUBULAR MEMBER, A PLURALITY OF LOAD SUPPORTING MEMBERS, EACH SAID MEMBER BEING PIVOTALLY CARRIED BY ONE OF SAID SPACED ARMS AND EACH BEING OPERATIVELY ARRANGED FOR ACTUATION TO A FIRST POSITION IN WHICH A LOAD IS HOOKED, AND A SECOND POSITION IN WHICH THE LOAD IS RELEASED, MEANS OPERATIVELY INTERCONNECTING SAID MOTOR WITH EACH OF SAID LOAD SUPPORTING MEMBERS TO SIMULTANEOUSLY PIVOT SAID LOAD SUPPORTING MEMBERS TO SIMULTANEOUSLY POSITIONS TO THE OTHER WHEN SAID MOTOR IS OPERATED, AND LOCKING MEANS OPERATIVELY CONNECTED TO SAID MOTOR TO PREVENT PIVOTAL MOVEMENT OF SAID LOAD SUPPORTING MEMBERS WHEN SAID MEMBERS ARE ACTUATED TO SAID SAID FIRST POSITION. 